Service model re-computation based on configuration item change type

ABSTRACT

A computational instance of a remote network management platform includes a database that contains a plurality of CI records corresponding to a set of computing devices, a set of software applications, and a network-based service. The database also contains a definition of a service model that represents the set of computing devices, the set of software applications, and relationships therebetween that facilitate providing the network-based service. The computational instance also includes one or more server devices configured: to receive an indication of a change to a CI record of the plurality of CI record; add, to a change record table, a change record corresponding to the change to the CI record; select, for the service layer based on a change type specified in the change record, a service model re-computation mode; and re-compute a service layer in accordance with the service model re-computation mode.

BACKGROUND

Remote management of networks may involve a remote network managementplatform gathering information regarding the configuration andoperational aspects of a managed network. Traditionally, computingdevices and applications operating on a managed network were viewed inisolation. Thus, it was difficult to determine the impact that a problemwith a particular computing device or application would have onhigher-layer services provided by the managed network.

Service mapping is a set of operations through which the remote networkmanagement platform can discover and organize these computing devicesand applications, and represent the relationships therebetween. Servicemapping facilitates the representation of the hardware and softwarecomponents that jointly provide a service in a managed network. A remotenetwork management platform can maintain a service model that representsthe computing devices of a managed network, applications of the managednetwork, and relationships therebetween. From time to time, this servicemodel may be updated as the hardware and software componentscontributing to the service change, or in order to correct part of theservice model.

For some managed networks, the process of updating a service model canconsume significant processing resources, thereby negatively affectingthe performance of the remote network management platform. Improvementsare therefore desired.

SUMMARY

The service model for a managed network can represent any devices on themanaged network, any applications or services executing thereon, as wellas relationships between devices, applications, and services. Each ofthe devices, applications, and/or services can be referred to asconfiguration items (CIs). Further, each CI can be represented by acorresponding CI record in a configuration management database (CMDB).

One way to maintain a service model for such a managed network is tore-compute the services of the managed network using a re-computationprocess as CI records of the CMDB change. The re-computation process cansynchronize the CMDB with the service model by persisting changes in theCMDB into the service model. For a change affecting a given CI, there-computation process can involve updating the information for thegiven CI in the service model, and also re-building the topology of theservice model based on relations between the given CI and other CIs ofthe CMDB. Re-building the topology can involve identifying an entrypoint of a service to which the given CI relates, tracing the entrypoint to the given CI based on a set of relations between the given CIand the entry point, and resolving the set of relations into a graph.

Unfortunately, however, this re-computation process can be wasteful interms of consumption of memory and processing resources. For instance,for a CI change that does not affect a topology of the service model,re-building the topology of the service model may be unnecessary.

The embodiments herein address this and potentially other problems byvarying the manner in which a service model is re-computed depending ona type of change that is made to a CI record. When a change is made to aCI record of a CMDB, a server device can add a change recordcorresponding to the change to a change record table. The change recordcan specify a change type that is indicative of whether the changeaffects a topology of service model. The server device can use thechange type specified in the change record as a basis for selecting aservice model re-computation mode from among a plurality of servicemodel re-computation modes, and re-compute a service layer of theservice model in accordance with the selected service modelre-computation mode.

Accordingly, a first example embodiment may involve a computationalinstance of a remote network management platform. The computationalinstance may include a database that contains a plurality of CI recordscorresponding to a set of computing devices disposed within a managednetwork, a set of software applications configured to execute on the setof computing devices, and a network-based service that is provided byexecution of the set of software applications. The managed network maybe associated with the computational instance. Further, the database maycontain a definition of a service model that represents the set ofcomputing devices, the set of software applications, and relationshipstherebetween that facilitate providing the network-based service. Theservice model may include a service environment having multiple servicelayers that are hierarchically-arranged within the service environment.The computational instance may also include one or more server devicesconfigured to receive, from the managed network, an indication of achange to a CI record of the plurality of CI records. The one or moreserver devices may also be configured to store, in the database, the CIrecord as changed and add, to a change record table stored within thedatabase, a change record corresponding to the change to the CI record.The change record may reference the CI record and a service layer of themultiple service layers, and may specify a change type that isindicative of whether the change affects a topology of the servicemodel. The one or more server devices may also be configured to select,for the service layer based on the change type, a service modelre-computation mode from among a plurality of service modelre-computation modes. And the one or more server devices may beconfigured to re-compute the service layer of the service environment inaccordance with the service model re-computation mode.

In a second example embodiment, a method may involve maintaining, by oneor more server devices of a computational instance, a database thatcontains a plurality of CI records corresponding to a set of computingdevices within a managed network, a set of software applicationsconfigured to execute on the set of computing devices, and anetwork-based service that is provided by execution of the set ofsoftware applications. The managed network may be associated with thecomputational instance. Further, the database may contain a definitionof a service model that represents the set of computing devices, the setof software applications, and relationships therebetween that facilitateproviding the network-based service. The service model may include aservice environment having multiple service layers that arehierarchically-arranged. The method may also involve receiving, by theone or more server devices, from the managed network, an indication of achange to a CI record of the plurality of CI records. In addition, themethod may involve storing, in the database, the CI record as changedand adding, by the one or more server devices, to a change record tablestored within the database, a change record corresponding to the changeto the CI record. The change record may reference the CI record and aservice layer of the multiple service layers, and may specify a changetype that is indicative of whether the change affects a topology of theservice model. Further, the method may involve selecting, by the one ormore server devices based on the change type, for the service layer, aservice model re-computation mode from among a plurality of servicemodel re-computation modes. And the method may involve re-computing, bythe one or more server devices, the service layer of the serviceenvironment in accordance with the service model re-computation mode.

In a third example embodiment, an article of manufacture may include anon-transitory computer-readable medium, having stored thereon programinstructions that, upon execution by one or more server devices of acomputational instance of a remote network management platform, causethe one or more server devices to perform operations in accordance withthe second example embodiment.

In a fourth example embodiment, a computing system may include at leastone processor, as well as memory and program instructions. The programinstructions may be stored in the memory, and upon execution by the atleast one processor, cause the computing system to perform operations inaccordance with the second example embodiment.

In a fifth example embodiment, a system may include various means forcarrying out each of the operations of the second example embodiment.

These, as well as other embodiments, aspects, advantages, andalternatives, will become apparent to those of ordinary skill in the artby reading the following detailed description, with reference whereappropriate to the accompanying drawings. Further, this summary andother descriptions and figures provided herein are intended toillustrate embodiments by way of example only and, as such, thatnumerous variations are possible. For instance, structural elements andprocess steps can be rearranged, combined, distributed, eliminated, orotherwise changed, while remaining within the scope of the embodimentsas claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a schematic drawing of a computing device, inaccordance with example embodiments.

FIG. 2 illustrates a schematic drawing of a server device cluster, inaccordance with example embodiments.

FIG. 3 depicts a remote network management architecture, in accordancewith example embodiments.

FIG. 4 depicts a communication environment involving a remote networkmanagement architecture, in accordance with example embodiments.

FIG. 5A depicts another communication environment involving a remotenetwork management architecture, in accordance with example embodiments.

FIG. 5B is a flow chart, in accordance with example embodiments.

FIG. 6 is a schematic drawing of a structure of a service model, inaccordance with example embodiments.

FIG. 7 depicts a service map representing computing devices andapplications, in accordance with example embodiments.

FIG. 8 depicts a change record table, in accordance with exampleembodiments.

FIG. 9 is a flow chart, in accordance with example embodiments.

FIG. 10 is another flow chart, in accordance with example embodiments.

FIG. 11 is another flow chart, in accordance with example embodiments.

DETAILED DESCRIPTION

Example methods, devices, and systems are described herein. It should beunderstood that the words “example” and “exemplary” are used herein tomean “serving as an example, instance, or illustration.” Any embodimentor feature described herein as being an “example” or “exemplary” is notnecessarily to be construed as preferred or advantageous over otherembodiments or features unless stated as such. Thus, other embodimentscan be utilized and other changes can be made without departing from thescope of the subject matter presented herein.

Accordingly, the example embodiments described herein are not meant tobe limiting. It will be readily understood that the aspects of thepresent disclosure, as generally described herein, and illustrated inthe figures, can be arranged, substituted, combined, separated, anddesigned in a wide variety of different configurations. For example, theseparation of features into “client” and “server” components may occurin a number of ways.

Further, unless context suggests otherwise, the features illustrated ineach of the figures may be used in combination with one another. Thus,the figures should be generally viewed as component aspects of one ormore overall embodiments, with the understanding that not allillustrated features are necessary for each embodiment.

Additionally, any enumeration of elements, blocks, or steps in thisspecification or the claims is for purposes of clarity. Thus, suchenumeration should not be interpreted to require or imply that theseelements, blocks, or steps adhere to a particular arrangement or arecarried out in a particular order.

I Introduction

A large enterprise is a complex entity with many interrelatedoperations. Some of these are found across the enterprise, such as humanresources (HR), supply chain, information technology (IT), and finance.However, each enterprise also has its own unique operations that provideessential capabilities and/or create competitive advantages.

To support widely-implemented operations, enterprises typically useoff-the-shelf software applications, such as customer relationshipmanagement (CRM) and human capital management (HCM) packages. However,they may also need custom software applications to meet their own uniquerequirements. A large enterprise often has dozens or hundreds of thesecustom software applications. Nonetheless, the advantages provided bythe embodiments herein are not limited to large enterprises and may beapplicable to an enterprise, or any other type of organization, of anysize.

Many such software applications are developed by individual departmentswithin the enterprise. These range from simple spreadsheets tocustom-built software tools and databases. But the proliferation ofsiloed custom software applications has numerous disadvantages. Itnegatively impacts an enterprise's ability to run and grow itsoperations, innovate, and meet regulatory requirements. The enterprisemay find it difficult to integrate, streamline and enhance itsoperations due to lack of a single system that unifies its subsystemsand data.

To efficiently create custom applications, enterprises would benefitfrom a remotely-hosted application platform that eliminates unnecessarydevelopment complexity. The goal of such a platform would be to reducetime-consuming, repetitive application development tasks so thatsoftware engineers and individuals in other roles can focus ondeveloping unique, high-value features.

In order to achieve this goal, the concept of Application Platform as aService (aPaaS) is introduced, to intelligently automate workflowsthroughout the enterprise. An aPaaS system is hosted remotely from theenterprise, but may access data, applications, and services within theenterprise by way of secure connections. Such an aPaaS system may have anumber of advantageous capabilities and characteristics. Theseadvantages and characteristics may be able to improve the enterprise'soperations and workflow for IT, HR, CRM, customer service, applicationdevelopment, and security.

The aPaaS system may support development and execution ofmodel-view-controller (MVC) applications. MVC applications divide theirfunctionality into three interconnected parts (model, view, andcontroller) in order to isolate representations of information from themanner in which the information is presented to the user, therebyallowing for efficient code reuse and parallel development. Theseapplications may be web-based, and offer create, read, update, delete(CRUD) capabilities. This allows new applications to be built on acommon application infrastructure.

The aPaaS system may support standardized application components, suchas a standardized set of widgets for graphical user interface (GUI)development. In this way, applications built using the aPaaS system havea common look and feel. Other software components and modules may bestandardized as well. In some cases, this look and feel can be brandedor skinned with an enterprise's custom logos and/or color schemes.

The aPaaS system may support the ability to configure the behavior ofapplications using metadata. This allows application behaviors to berapidly adapted to meet specific needs. Such an approach reducesdevelopment time and increases flexibility. Further, the aPaaS systemmay support GUI tools that facilitate metadata creation and management,thus reducing errors in the metadata.

The aPaaS system may support clearly-defined interfaces betweenapplications, so that software developers can avoid unwantedinter-application dependencies. Thus, the aPaaS system may implement aservice layer in which persistent state information and other data arestored.

The aPaaS system may support a rich set of integration features so thatthe applications thereon can interact with legacy applications andthird-party applications. For instance, the aPaaS system may support acustom employee-onboarding system that integrates with legacy HR, IT,and accounting systems.

The aPaaS system may support enterprise-grade security. Furthermore,since the aPaaS system may be remotely hosted, it should also utilizesecurity procedures when it interacts with systems in the enterprise orthird-party networks and services hosted outside of the enterprise. Forexample, the aPaaS system may be configured to share data amongst theenterprise and other parties to detect and identify common securitythreats.

Other features, functionality, and advantages of an aPaaS system mayexist. This description is for purpose of example and is not intended tobe limiting.

As an example of the aPaaS development process, a software developer maybe tasked to create a new application using the aPaaS system. First, thedeveloper may define the data model, which specifies the types of datathat the application uses and the relationships therebetween. Then, viaa GUI of the aPaaS system, the developer enters (e.g., uploads) the datamodel. The aPaaS system automatically creates all of the correspondingdatabase tables, fields, and relationships, which can then be accessedvia an object-oriented services layer.

In addition, the aPaaS system can also build a fully-functional MVCapplication with client-side interfaces and server-side CRUD logic. Thisgenerated application may serve as the basis of further development forthe user. Advantageously, the developer does not have to spend a largeamount of time on basic application functionality. Further, since theapplication may be web-based, it can be accessed from anyInternet-enabled client device. Alternatively or additionally, a localcopy of the application may be able to be accessed, for instance, whenInternet service is not available.

The aPaaS system may also support a rich set of pre-definedfunctionality that can be added to applications. These features includesupport for searching, email, templating, workflow design, reporting,analytics, social media, scripting, mobile-friendly output, andcustomized GUIs.

The following embodiments describe architectural and functional aspectsof example aPaaS systems, as well as the features and advantagesthereof.

II. Example Computing Devices and Cloud-Based Computing Environments

FIG. 1 is a simplified block diagram exemplifying a computing device100, illustrating some of the components that could be included in acomputing device arranged to operate in accordance with the embodimentsherein. Computing device 100 could be a client device (e.g., a deviceactively operated by a user), a server device (e.g., a device thatprovides computational services to client devices), or some other typeof computational platform. Some server devices may operate as clientdevices from time to time in order to perform particular operations, andsome client devices may incorporate server features.

In this example, computing device 100 includes processor 102, memory104, network interface 106, and an input/output unit 108, all of whichmay be coupled by a system bus 110 or a similar mechanism. In someembodiments, computing device 100 may include other components and/orperipheral devices (e.g., detachable storage, printers, and so on).

Processor 102 may be one or more of any type of computer processingelement, such as a central processing unit (CPU), a co-processor (e.g.,a mathematics, graphics, or encryption co-processor), a digital signalprocessor (DSP), a network processor, and/or a form of integratedcircuit or controller that performs processor operations. In some cases,processor 102 may be one or more single-core processors. In other cases,processor 102 may be one or more multi-core processors with multipleindependent processing units. Processor 102 may also include registermemory for temporarily storing instructions being executed and relateddata, as well as cache memory for temporarily storing recently-usedinstructions and data.

Memory 104 may be any form of computer-usable memory, including but notlimited to random access memory (RAM), read-only memory (ROM), andnon-volatile memory (e.g., flash memory, hard disk drives, solid statedrives, compact discs (CDs), digital video discs (DVDs), and/or tapestorage). Thus, memory 104 represents both main memory units, as well aslong-term storage. Other types of memory may include biological memory.

Memory 104 may store program instructions and/or data on which programinstructions may operate. By way of example, memory 104 may store theseprogram instructions on a non-transitory, computer-readable medium, suchthat the instructions are executable by processor 102 to carry out anyof the methods, processes, or operations disclosed in this specificationor the accompanying drawings.

As shown in FIG. 1, memory 104 may include firmware 104A, kernel 104B,and/or applications 104C. Firmware 104A may be program code used to bootor otherwise initiate some or all of computing device 100. Kernel 104Bmay be an operating system, including modules for memory management,scheduling and management of processes, input/output, and communication.Kernel 104B may also include device drivers that allow the operatingsystem to communicate with the hardware modules (e.g., memory units,networking interfaces, ports, and busses), of computing device 100.Applications 104C may be one or more user-space software programs, suchas web browsers or email clients, as well as any software libraries usedby these programs. Memory 104 may also store data used by these andother programs and applications.

Network interface 106 may take the form of one or more wirelineinterfaces, such as Ethernet (e.g., Fast Ethernet, Gigabit Ethernet, andso on). Network interface 106 may also support communication over one ormore non-Ethernet media, such as coaxial cables or power lines, or overwide-area media, such as Synchronous Optical Networking (SONET) ordigital subscriber line (DSL) technologies. Network interface 106 mayadditionally take the form of one or more wireless interfaces, such asIEEE 802.11 (Wifi), BLUETOOTH®, global positioning system (GPS), or awide-area wireless interface. However, other forms of physical layerinterfaces and other types of standard or proprietary communicationprotocols may be used over network interface 106. Furthermore, networkinterface 106 may comprise multiple physical interfaces. For instance,some embodiments of computing device 100 may include Ethernet,BLUETOOTH®, and Wifi interfaces.

Input/output unit 108 may facilitate user and peripheral deviceinteraction with computing device 100. Input/output unit 108 may includeone or more types of input devices, such as a keyboard, a mouse, a touchscreen, and so on. Similarly, input/output unit 108 may include one ormore types of output devices, such as a screen, monitor, printer, and/orone or more light emitting diodes (LEDs). Additionally or alternatively,computing device 100 may communicate with other devices using auniversal serial bus (USB) or high-definition multimedia interface(HDMI) port interface, for example.

In some embodiments, one or more computing devices like computing device100 may be deployed to support an aPaaS architecture. The exact physicallocation, connectivity, and configuration of these computing devices maybe unknown and/or unimportant to client devices. Accordingly, thecomputing devices may be referred to as “cloud-based” devices that maybe housed at various remote data center locations.

FIG. 2 depicts a cloud-based server cluster 200 in accordance withexample embodiments. In FIG. 2, operations of a computing device (e.g.,computing device 100) may be distributed between server devices 202,data storage 204, and routers 206, all of which may be connected bylocal cluster network 208. The number of server devices 202, datastorages 204, and routers 206 in server cluster 200 may depend on thecomputing task(s) and/or applications assigned to server cluster 200.

For example, server devices 202 can be configured to perform variouscomputing tasks of computing device 100. Thus, computing tasks can bedistributed among one or more of server devices 202. To the extent thatthese computing tasks can be performed in parallel, such a distributionof tasks may reduce the total time to complete these tasks and return aresult. For purpose of simplicity, both server cluster 200 andindividual server devices 202 may be referred to as a “server device.”This nomenclature should be understood to imply that one or moredistinct server devices, data storage devices, and cluster routers maybe involved in server device operations.

Data storage 204 may be data storage arrays that include drive arraycontrollers configured to manage read and write access to groups of harddisk drives and/or solid state drives. The drive array controllers,alone or in conjunction with server devices 202, may also be configuredto manage backup or redundant copies of the data stored in data storage204 to protect against drive failures or other types of failures thatprevent one or more of server devices 202 from accessing units of datastorage 204. Other types of memory aside from drives may be used.

Routers 206 may include networking equipment configured to provideinternal and external communications for server cluster 200. Forexample, routers 206 may include one or more packet-switching and/orrouting devices (including switches and/or gateways) configured toprovide (i) network communications between server devices 202 and datastorage 204 via local cluster network 208, and/or (ii) networkcommunications between the server cluster 200 and other devices viacommunication link 210 to network 212.

Additionally, the configuration of routers 206 can be based at least inpart on the data communication requirements of server devices 202 anddata storage 204, the latency and throughput of the local clusternetwork 208, the latency, throughput, and cost of communication link210, and/or other factors that may contribute to the cost, speed,fault-tolerance, resiliency, efficiency and/or other design goals of thesystem architecture.

As a possible example, data storage 204 may include any form ofdatabase, such as a structured query language (SQL) database. Varioustypes of data structures may store the information in such a database,including but not limited to tables, arrays, lists, trees, and tuples.Furthermore, any databases in data storage 204 may be monolithic ordistributed across multiple physical devices.

Server devices 202 may be configured to transmit data to and receivedata from data storage 204. This transmission and retrieval may take theform of SQL queries or other types of database queries, and the outputof such queries, respectively. Additional text, images, video, and/oraudio may be included as well. Furthermore, server devices 202 mayorganize the received data into web page representations. Such arepresentation may take the form of a markup language, such as thehypertext markup language (HTML), the extensible markup language (XML),or some other standardized or proprietary format. Moreover, serverdevices 202 may have the capability of executing various types ofcomputerized scripting languages, such as but not limited to Perl,Python, PHP Hypertext Preprocessor (PHP), Active Server Pages (ASP),JavaScript, and so on. Computer program code written in these languagesmay facilitate the providing of web pages to client devices, as well asclient device interaction with the web pages.

III. Example Remote Network Management Architecture

FIG. 3 depicts a remote network management architecture, in accordancewith example embodiments. This architecture includes three maincomponents, managed network 300, remote network management platform 320,and third-party networks 340, all connected by way of Internet 350.

Managed network 300 may be, for example, an enterprise network used byan entity for computing and communications tasks, as well as storage ofdata. Thus, managed network 300 may include various client devices 302,server devices 304, routers 306, virtual machines 308, firewall 310,and/or proxy servers 312. Client devices 302 may be embodied bycomputing device 100, server devices 304 may be embodied by computingdevice 100 or server cluster 200, and routers 306 may be any type ofrouter, switch, or gateway.

Virtual machines 308 may be embodied by one or more of computing device100 or server cluster 200. In general, a virtual machine is an emulationof a computing system, and mimics the functionality (e.g., processor,memory, and communication resources) of a physical computer. Onephysical computing system, such as server cluster 200, may support up tothousands of individual virtual machines. In some embodiments, virtualmachines 308 may be managed by a centralized server device orapplication that facilitates allocation of physical computing resourcesto individual virtual machines, as well as performance and errorreporting. Enterprises often employ virtual machines in order toallocate computing resources in an efficient, as needed fashion.Providers of virtualized computing systems include VMWARE® andMICROSOFT®.

Firewall 310 may be one or more specialized routers or server devicesthat protect managed network 300 from unauthorized attempts to accessthe devices, applications, and services therein, while allowingauthorized communication that is initiated from managed network 300.Firewall 310 may also provide intrusion detection, web filtering, virusscanning, application-layer gateways, and other applications orservices. In some embodiments not shown in FIG. 3, managed network 300may include one or more virtual private network (VPN) gateways withwhich it communicates with remote network management platform 320 (seebelow).

Managed network 300 may also include one or more proxy servers 312. Anembodiment of proxy servers 312 may be a server device that facilitatescommunication and movement of data between managed network 300, remotenetwork management platform 320, and third-party networks 340. Inparticular, proxy servers 312 may be able to establish and maintainsecure communication sessions with one or more computational instancesof remote network management platform 320. By way of such a session,remote network management platform 320 may be able to discover andmanage aspects of the architecture and configuration of managed network300 and its components. Possibly with the assistance of proxy servers312, remote network management platform 320 may also be able to discoverand manage aspects of third-party networks 340 that are used by managednetwork 300.

Firewalls, such as firewall 310, typically deny all communicationsessions that are incoming by way of Internet 350, unless such a sessionwas ultimately initiated from behind the firewall (i.e., from a deviceon managed network 300) or the firewall has been explicitly configuredto support the session. By placing proxy servers 312 behind firewall 310(e.g., within managed network 300 and protected by firewall 310), proxyservers 312 may be able to initiate these communication sessions throughfirewall 310. Thus, firewall 310 might not have to be specificallyconfigured to support incoming sessions from remote network managementplatform 320, thereby avoiding potential security risks to managednetwork 300.

In some cases, managed network 300 may consist of a few devices and asmall number of networks. In other deployments, managed network 300 mayspan multiple physical locations and include hundreds of networks andhundreds of thousands of devices. Thus, the architecture depicted inFIG. 3 is capable of scaling up or down by orders of magnitude.

Furthermore, depending on the size, architecture, and connectivity ofmanaged network 300, a varying number of proxy servers 312 may bedeployed therein. For example, each one of proxy servers 312 may beresponsible for communicating with remote network management platform320 regarding a portion of managed network 300. Alternatively oradditionally, sets of two or more proxy servers may be assigned to sucha portion of managed network 300 for purposes of load balancing,redundancy, and/or high availability.

Remote network management platform 320 is a hosted environment thatprovides aPaaS services to users, particularly to the operators ofmanaged network 300. These services may take the form of web-basedportals, for instance. Thus, a user can securely access remote networkmanagement platform 320 from, for instance, client devices 302, orpotentially from a client device outside of managed network 300. By wayof the web-based portals, users may design, test, and deployapplications, generate reports, view analytics, and perform other tasks.

As shown in FIG. 3, remote network management platform 320 includes fourcomputational instances 322, 324, 326, and 328. Each of these instancesmay represent one or more server devices and/or one or more databasesthat provide a set of web portals, services, and applications (e.g., awholly-functioning aPaaS system) available to a particular customer. Insome cases, a single customer may use multiple computational instances.For example, managed network 300 may be an enterprise customer of remotenetwork management platform 320, and may use computational instances322, 324, and 326. The reason for providing multiple instances to onecustomer is that the customer may wish to independently develop, test,and deploy its applications and services. Thus, computational instance322 may be dedicated to application development related to managednetwork 300, computational instance 324 may be dedicated to testingthese applications, and computational instance 326 may be dedicated tothe live operation of tested applications and services. A computationalinstance may also be referred to as a hosted instance, a remoteinstance, a customer instance, or by some other designation. Anyapplication deployed onto a computational instance may be a scopedapplication, in that its access to databases within the computationalinstance can be restricted to certain elements therein (e.g., one ormore particular database tables or particular rows with one or moredatabase tables).

For purpose of clarity, the disclosure herein refers to the physicalhardware, software, and arrangement thereof as a “computationalinstance.” Note that users may colloquially refer to the graphical userinterfaces provided thereby as “instances.” But unless it is definedotherwise herein, a “computational instance” is a computing systemdisposed within remote network management platform 320.

The multi-instance architecture of remote network management platform320 is in contrast to conventional multi-tenant architectures, overwhich multi-instance architectures have several advantages. Inmulti-tenant architectures, data from different customers (e.g.,enterprises) are comingled in a single database. While these customers'data are separate from one another, the separation is enforced by thesoftware that operates the single database. As a consequence, a securitybreach in this system may impact all customers' data, creatingadditional risk, especially for entities subject to governmental,healthcare, and/or financial regulation. Furthermore, any databaseoperations that impact one customer will likely impact all customerssharing that database. Thus, if there is an outage due to hardware orsoftware errors, this outage affects all such customers. Likewise, ifthe database is to be upgraded to meet the needs of one customer, itwill be unavailable to all customers during the upgrade process. Often,such maintenance windows will be long, due to the size of the shareddatabase.

In contrast, the multi-instance architecture provides each customer withits own database in a dedicated computing instance. This preventscomingling of customer data, and allows each instance to beindependently managed. For example, when one customer's instanceexperiences an outage due to errors or an upgrade, other computationalinstances are not impacted. Maintenance down time is limited because thedatabase only contains one customer's data. Further, the simpler designof the multi-instance architecture allows redundant copies of eachcustomer database and instance to be deployed in a geographicallydiverse fashion. This facilitates high availability, where the liveversion of the customer's instance can be moved when faults are detectedor maintenance is being performed.

In some embodiments, remote network management platform 320 may includeone or more central instances, controlled by the entity that operatesthis platform. Like a computational instance, a central instance mayinclude some number of physical or virtual servers and database devices.Such a central instance may serve as a repository for data that can beshared amongst at least some of the computational instances. Forinstance, definitions of common security threats that could occur on thecomputational instances, software packages that are commonly discoveredon the computational instances, and/or an application store forapplications that can be deployed to the computational instances mayreside in a central instance. Computational instances may communicatewith central instances by way of well-defined interfaces in order toobtain this data.

In order to support multiple computational instances in an efficientfashion, remote network management platform 320 may implement aplurality of these instances on a single hardware platform. For example,when the aPaaS system is implemented on a server cluster such as servercluster 200, it may operate a virtual machine that dedicates varyingamounts of computational, storage, and communication resources toinstances. But full virtualization of server cluster 200 might not benecessary, and other mechanisms may be used to separate instances. Insome examples, each instance may have a dedicated account and one ormore dedicated databases on server cluster 200. Alternatively,computational instance 322 may span multiple physical devices.

In some cases, a single server cluster of remote network managementplatform 320 may support multiple independent enterprises. Furthermore,as described below, remote network management platform 320 may includemultiple server clusters deployed in geographically diverse data centersin order to facilitate load balancing, redundancy, and/or highavailability.

Third-party networks 340 may be remote server devices (e.g., a pluralityof server clusters such as server cluster 200) that can be used foroutsourced computational, data storage, communication, and servicehosting operations. These servers may be virtualized (i.e., the serversmay be virtual machines). Examples of third-party networks 340 mayinclude AMAZON WEB SERVICES® and MICROSOFT® Azure. Like remote networkmanagement platform 320, multiple server clusters supporting third-partynetworks 340 may be deployed at geographically diverse locations forpurposes of load balancing, redundancy, and/or high availability.

Managed network 300 may use one or more of third-party networks 340 todeploy applications and services to its clients and customers. Forinstance, if managed network 300 provides online music streamingservices, third-party networks 340 may store the music files and provideweb interface and streaming capabilities. In this way, the enterprise ofmanaged network 300 does not have to build and maintain its own serversfor these operations.

Remote network management platform 320 may include modules thatintegrate with third-party networks 340 to expose virtual machines andmanaged services therein to managed network 300. The modules may allowusers to request virtual resources and provide flexible reporting forthird-party networks 340. In order to establish this functionality, auser from managed network 300 might first establish an account withthird-party networks 340, and request a set of associated resources.Then, the user may enter the account information into the appropriatemodules of remote network management platform 320. These modules maythen automatically discover the manageable resources in the account, andalso provide reports related to usage, performance, and billing.

Internet 350 may represent a portion of the global Internet. However,Internet 350 may alternatively represent a different type of network,such as a private wide-area or local-area packet-switched network.

FIG. 4 further illustrates the communication environment between managednetwork 300 and computational instance 322, and introduces additionalfeatures and alternative embodiments. In FIG. 4, computational instance322 is replicated across data centers 400A and 400B. These data centersmay be geographically distant from one another, perhaps in differentcities or different countries. Each data center includes supportequipment that facilitates communication with managed network 300, aswell as remote users.

In data center 400A, network traffic to and from external devices flowseither through VPN gateway 402A or firewall 404A. VPN gateway 402A maybe peered with VPN gateway 412 of managed network 300 by way of asecurity protocol such as Internet Protocol Security (IPSEC) orTransport Layer Security (TLS). Firewall 404A may be configured to allowaccess from authorized users, such as user 414 and remote user 416, andto deny access to unauthorized users. By way of firewall 404A, theseusers may access computational instance 322, and possibly othercomputational instances. Load balancer 406A may be used to distributetraffic amongst one or more physical or virtual server devices that hostcomputational instance 322. Load balancer 406A may simplify user accessby hiding the internal configuration of data center 400A, (e.g.,computational instance 322) from client devices. For instance, ifcomputational instance 322 includes multiple physical or virtualcomputing devices that share access to multiple databases, load balancer406A may distribute network traffic and processing tasks across thesecomputing devices and databases so that no one computing device ordatabase is significantly busier than the others. In some embodiments,computational instance 322 may include VPN gateway 402A, firewall 404A,and load balancer 406A.

Data center 400B may include its own versions of the components in datacenter 400A. Thus, VPN gateway 402B, firewall 404B, and load balancer406B may perform the same or similar operations as VPN gateway 402A,firewall 404A, and load balancer 406A, respectively. Further, by way ofreal-time or near-real-time database replication and/or otheroperations, computational instance 322 may exist simultaneously in datacenters 400A and 400B.

Data centers 400A and 400B as shown in FIG. 4 may facilitate redundancyand high availability. In the configuration of FIG. 4, data center 400Ais active and data center 400B is passive. Thus, data center 400A isserving all traffic to and from managed network 300, while the versionof computational instance 322 in data center 400B is being updated innear-real-time. Other configurations, such as one in which both datacenters are active, may be supported.

Should data center 400A fail in some fashion or otherwise becomeunavailable to users, data center 400B can take over as the active datacenter. For example, domain name system (DNS) servers that associate adomain name of computational instance 322 with one or more InternetProtocol (IP) addresses of data center 400A may re-associate the domainname with one or more IP addresses of data center 400B. After thisre-association completes (which may take less than one second or severalseconds), users may access computational instance 322 by way of datacenter 400B.

FIG. 4 also illustrates a possible configuration of managed network 300.As noted above, proxy servers 312 and user 414 may access computationalinstance 322 through firewall 310. Proxy servers 312 may also accessconfiguration items 410. In FIG. 4, configuration items 410 may refer toany or all of client devices 302, server devices 304, routers 306, andvirtual machines 308, any applications or services executing thereon, aswell as relationships between devices, applications, and services. Thus,the term “configuration items” may be shorthand for any physical orvirtual device, or any application or service remotely discoverable ormanaged by computational instance 322, or relationships betweendiscovered devices, applications, and services. Configuration items maybe represented in a CMDB of computational instance 322.

As noted above, VPN gateway 412 may provide a dedicated VPN to VPNgateway 402A. Such a VPN may be helpful when there is a significantamount of traffic between managed network 300 and computational instance322, or security policies otherwise suggest or require use of a VPNbetween these sites. In some embodiments, any device in managed network300 and/or computational instance 322 that directly communicates via theVPN is assigned a public IP address. Other devices in managed network300 and/or computational instance 322 may be assigned private IPaddresses (e.g., IP addresses selected from the 10.0.0.0-10.255.255.255or 192.168.0.0-192.168.255.255 ranges, represented in shorthand assubnets 10.0.0.0/8 and 192.168.0.0/16, respectively).

IV. Example Device, Application, and Service Discovery

In order for remote network management platform 320 to administer thedevices, applications, and services of managed network 300, remotenetwork management platform 320 may first determine what devices arepresent in managed network 300, the configurations and operationalstatuses of these devices, and the applications and services provided bythe devices, and well as the relationships between discovered devices,applications, and services. As noted above, each device, application,service, and relationship may be referred to as a configuration item.The process of defining configuration items within managed network 300is referred to as discovery, and may be facilitated at least in part byproxy servers 312.

For purpose of the embodiments herein, an “application” may refer to oneor more processes, threads, programs, client modules, server modules, orany other software that executes on a device or group of devices. A“service” may refer to a high-level capability provided by multipleapplications executing on one or more devices working in conjunctionwith one another. For example, a high-level web service may involvemultiple web application server threads executing on one device andaccessing information from a database application that executes onanother device.

FIG. 5A provides a logical depiction of how configuration items can bediscovered, as well as how information related to discoveredconfiguration items can be stored. For sake of simplicity, remotenetwork management platform 320, third-party networks 340, and Internet350 are not shown.

In FIG. 5A, CMDB 500 and task list 502 are stored within computationalinstance 322. Computational instance 322 may transmit discovery commandsto proxy servers 312. In response, proxy servers 312 may transmit probesto various devices, applications, and services in managed network 300.These devices, applications, and services may transmit responses toproxy servers 312, and proxy servers 312 may then provide informationregarding discovered configuration items to CMDB 500 for storagetherein. Configuration items stored in CMDB 500 represent theenvironment of managed network 300.

Task list 502 represents a list of activities that proxy servers 312 areto perform on behalf of computational instance 322. As discovery takesplace, task list 502 is populated. Proxy servers 312 repeatedly querytask list 502, obtain the next task therein, and perform this task untiltask list 502 is empty or another stopping condition has been reached.

To facilitate discovery, proxy servers 312 may be configured withinformation regarding one or more subnets in managed network 300 thatare reachable by way of proxy servers 312. For instance, proxy servers312 may be given the IP address range 192.168.0/24 as a subnet. Then,computational instance 322 may store this information in CMDB 500 andplace tasks in task list 502 for discovery of devices at each of theseaddresses.

FIG. 5A also depicts devices, applications, and services in managednetwork 300 as configuration items 504, 506, 508, 510, and 512. As notedabove, these configuration items represent a set of physical and/orvirtual devices (e.g., client devices, server devices, routers, orvirtual machines), applications executing thereon (e.g., web servers,email servers, databases, or storage arrays), relationshipstherebetween, as well as services that involve multiple individualconfiguration items.

Placing the tasks in task list 502 may trigger or otherwise cause proxyservers 312 to begin discovery. Alternatively or additionally, discoverymay be manually triggered or automatically triggered based on triggeringevents (e.g., discovery may automatically begin once per day at aparticular time).

In general, discovery may proceed in four logical phases: scanning,classification, identification, and exploration. Each phase of discoveryinvolves various types of probe messages being transmitted by proxyservers 312 to one or more devices in managed network 300. The responsesto these probes may be received and processed by proxy servers 312, andrepresentations thereof may be transmitted to CMDB 500. Thus, each phasecan result in more configuration items being discovered and stored inCMDB 500.

In the scanning phase, proxy servers 312 may probe each IP address inthe specified range of IP addresses for open Transmission ControlProtocol (TCP) and/or User Datagram Protocol (UDP) ports to determinethe general type of device. The presence of such open ports at an IPaddress may indicate that a particular application is operating on thedevice that is assigned the IP address, which in turn may identify theoperating system used by the device. For example, if TCP port 135 isopen, then the device is likely executing a WINDOWS® operating system.Similarly, if TCP port 22 is open, then the device is likely executing aUNIX® operating system, such as LINUX®. If UDP port 161 is open, thenthe device may be able to be further identified through the SimpleNetwork Management Protocol (SNMP). Other possibilities exist. Once thepresence of a device at a particular IP address and its open ports havebeen discovered, these configuration items are saved in CMDB 500.

In the classification phase, proxy servers 312 may further probe eachdiscovered device to determine the version of its operating system. Theprobes used for a particular device are based on information gatheredabout the devices during the scanning phase. For example, if a device isfound with TCP port 22 open, a set of UNIX®-specific probes may be used.Likewise, if a device is found with TCP port 135 open, a set ofWINDOWS®-specific probes may be used. For either case, an appropriateset of tasks may be placed in task list 502 for proxy servers 312 tocarry out. These tasks may result in proxy servers 312 logging on, orotherwise accessing information from the particular device. Forinstance, if TCP port 22 is open, proxy servers 312 may be instructed toinitiate a Secure Shell (SSH) connection to the particular device andobtain information about the operating system thereon from particularlocations in the file system. Based on this information, the operatingsystem may be determined. As an example, a UNIX® device with TCP port 22open may be classified as AIX®, HPUX, LINUX®, MACOS®, or SOLARIS®. Thisclassification information may be stored as one or more configurationitems in CMDB 500.

In the identification phase, proxy servers 312 may determine specificdetails about a classified device. The probes used during this phase maybe based on information gathered about the particular devices during theclassification phase. For example, if a device was classified as LINUX®,a set of LINUX®-specific probes may be used. Likewise, if a device wasclassified as WINDOWS® 2012, as a set of WINDOWS®-2012-specific probesmay be used. As was the case for the classification phase, anappropriate set of tasks may be placed in task list 502 for proxyservers 312 to carry out. These tasks may result in proxy servers 312reading information from the particular device, such as basicinput/output system (BIOS) information, serial numbers, networkinterface information, media access control address(es) assigned tothese network interface(s), IP address(es) used by the particular deviceand so on. This identification information may be stored as one or moreconfiguration items in CMDB 500.

In the exploration phase, proxy servers 312 may determine furtherdetails about the operational state of a classified device. The probesused during this phase may be based on information gathered about theparticular devices during the classification phase and/or theidentification phase. Again, an appropriate set of tasks may be placedin task list 502 for proxy servers 312 to carry out. These tasks mayresult in proxy servers 312 reading additional information from theparticular device, such as processor information, memory information,lists of running processes (applications), and so on. Once more, thediscovered information may be stored as one or more configuration itemsin CMDB 500.

Running discovery on a network device, such as a router, may utilizeSNMP. Instead of or in addition to determining a list of runningprocesses or other application-related information, discovery maydetermine additional subnets known to the router and the operationalstate of the router's network interfaces (e.g., active, inactive, queuelength, number of packets dropped, etc.). The IP addresses of theadditional subnets may be candidates for further discovery procedures.Thus, discovery may progress iteratively or recursively.

Once discovery completes, a snapshot representation of each discovereddevice, application, and service is available in CMDB 500. For example,after discovery, operating system version, hardware configuration andnetwork configuration details for client devices, server devices, androuters in managed network 300, as well as applications executingthereon, may be stored. This collected information may be presented to auser in various ways to allow the user to view the hardware compositionand operational status of devices, as well as the characteristics ofservices that span multiple devices and applications.

Furthermore, CMDB 500 may include entries regarding dependencies andrelationships between configuration items. More specifically, anapplication that is executing on a particular server device, as well asthe services that rely on this application, may be represented as suchin CMDB 500. For instance, suppose that a database application isexecuting on a server device, and that this database application is usedby a new employee onboarding service as well as a payroll service. Thus,if the server device is taken out of operation for maintenance, it isclear that the employee onboarding service and payroll service will beimpacted. Likewise, the dependencies and relationships betweenconfiguration items may be able to represent the services impacted whena particular router fails.

In general, dependencies and relationships between configuration itemsmay be displayed on a web-based interface and represented in ahierarchical fashion. Thus, adding, changing, or removing suchdependencies and relationships may be accomplished by way of thisinterface.

Furthermore, users from managed network 300 may develop workflows thatallow certain coordinated activities to take place across multiplediscovered devices. For instance, an IT workflow might allow the user tochange the common administrator password to all discovered LINUX®devices in a single operation.

In order for discovery to take place in the manner described above,proxy servers 312, CMDB 500, and/or one or more credential stores may beconfigured with credentials for one or more of the devices to bediscovered. Credentials may include any type of information needed inorder to access the devices. These may include userid/password pairs,certificates, and so on. In some embodiments, these credentials may bestored in encrypted fields of CMDB 500. Proxy servers 312 may containthe decryption key for the credentials so that proxy servers 312 can usethese credentials to log on to or otherwise access devices beingdiscovered.

The discovery process is depicted as a flow chart in FIG. 5B. At block520, the task list in the computational instance is populated, forinstance, with a range of IP addresses. At block 522, the scanning phasetakes place. Thus, the proxy servers probe the IP addresses for devicesusing these IP addresses, and attempt to determine the operating systemsthat are executing on these devices. At block 524, the classificationphase takes place. The proxy servers attempt to determine the operatingsystem version of the discovered devices. At block 526, theidentification phase takes place. The proxy servers attempt to determinethe hardware and/or software configuration of the discovered devices. Atblock 528, the exploration phase takes place. The proxy servers attemptto determine the operational state and applications executing on thediscovered devices. At block 530, further editing of the configurationitems representing the discovered devices and applications may takeplace. This editing may be automated and/or manual in nature.

The blocks represented in FIG. 5B are for purpose of example. Discoverymay be a highly configurable procedure that can have more or fewerphases, and the operations of each phase may vary. In some cases, one ormore phases may be customized, or may otherwise deviate from theexemplary descriptions above.

V. CMDB Identification Rules and Reconciliation

A CMDB, such as CMDB 500, provides a repository of configuration items,and when properly provisioned, can take on a key role in higher-layerapplications deployed within or involving a computational instance.These applications may relate to enterprise IT service management,operations management, asset management, configuration management,compliance, and so on.

For example, an IT service management application may use information inthe CMDB to determine applications and services that may be impacted bya component (e.g., a server device) that has malfunctioned, crashed, oris heavily loaded. Likewise, an asset management application may useinformation in the CMDB to determine which hardware and/or softwarecomponents are being used to support particular enterprise applications.As a consequence of the importance of the CMDB, it is desirable for theinformation stored therein to be accurate, consistent, and up to date.

A CMDB may be populated in various ways. As discussed above, a discoveryprocedure may automatically store information related to configurationitems in the CMDB. However, a CMDB can also be populated, as a whole orin part, by manual entry, configuration files, and third-party datasources. Given that multiple data sources may be able to update the CMDBat any time, it is possible that one data source may overwrite entriesof another data source. Also, two data sources may each create slightlydifferent entries for the same configuration item, resulting in a CMDBcontaining duplicate data. When either of these occurrences takes place,they can cause the health and utility of the CMDB to be reduced.

In order to mitigate this situation, these data sources might not writeconfiguration items directly to the CMDB. Instead, they may write to anidentification and reconciliation application programming interface(API). This API may use a set of configurable identification rules thatcan be used to uniquely identify configuration items and determinewhether and how they are written to the CMDB.

In general, an identification rule specifies a set of configuration itemattributes that can be used for this unique identification.Identification rules may also have priorities so that rules with higherpriorities are considered before rules with lower priorities.Additionally, a rule may be independent, in that the rule identifiesconfiguration items independently of other configuration items.Alternatively, the rule may be dependent, in that the rule first uses ametadata rule to identify a dependent configuration item.

Metadata rules describe which other configuration items are containedwithin a particular configuration item, or the host on which aparticular configuration item is deployed. For example, a networkdirectory service configuration item may contain a domain controllerconfiguration item, while a web server application configuration itemmay be hosted on a server device configuration item.

A goal of each identification rule is to use a combination of attributesthat can unambiguously distinguish a configuration item from all otherconfiguration items, and is expected not to change during the lifetimeof the configuration item. Some possible attributes for an exampleserver device may include serial number, location, operating system,operating system version, memory capacity, and so on. If a rulespecifies attributes that do not uniquely identify the configurationitem, then multiple components may be represented as the sameconfiguration item in the CMDB. Also, if a rule specifies attributesthat change for a particular configuration item, duplicate configurationitems may be created.

Thus, when a data source provides information regarding a configurationitem to the identification and reconciliation API, the API may attemptto match the information with one or more rules. If a match is found,the configuration item is written to the CMDB. If a match is not found,the configuration item may be held for further analysis.

Configuration item reconciliation procedures may be used to ensure thatonly authoritative data sources are allowed to overwrite configurationitem data in the CMDB. This reconciliation may also be rules-based. Forinstance, a reconciliation rule may specify that a particular datasource is authoritative for a particular configuration item type and setof attributes. Then, the identification and reconciliation API will onlypermit this authoritative data source to write to the particularconfiguration item, and writes from unauthorized data sources may beprevented. Thus, the authorized data source becomes the single source oftruth regarding the particular configuration item. In some cases, anunauthorized data source may be allowed to write to a configuration itemif it is creating the configuration item or the attributes to which itis writing are empty.

Additionally, multiple data sources may be authoritative for the sameconfiguration item or attributes thereof. To avoid ambiguities, thesedata sources may be assigned precedences that are taken into accountduring the writing of configuration items. For example, a secondaryauthorized data source may be able to write to a configuration item'sattribute until a primary authorized data source writes to thisattribute. Afterward, further writes to the attribute by the secondaryauthorized data source may be prevented.

In some cases, duplicate configuration items may be automaticallydetected by reconciliation procedures or in another fashion. Theseconfiguration items may be flagged for manual de-duplication.

VI. Example Service Model

In line with the discussion above, a computational instance, such ascomputational instance 322, can store a database that contains adefinition of a service model. By way of example, FIG. 6 is a schematicdrawing illustrating an example structure of a service model 600.Service model 600 can represent CIs disposed within a managed network,such as a set of computing devices of a managed network and a set ofsoftware applications configured to execute on the set of computingdevices. In addition, service model 600 may be used to modelrelationships and connections between CIs as reflected in CMDB 500.

As shown in FIG. 6, service model 600 includes one or more servicecontainers 602 that contain information about various serviceenvironments 604 and 606. These service environments 604 and 606 enableseparating a service into various environments (e.g., development,production, testing, etc.). For example, service environment 604 maycorrespond to a first environment having first computing resources, andservice environment 606 may correspond to a second environment havingsecond computing resources.

Each of service environments 604 and 606 may include one or more servicelayers 608. Service layers 608 may include information and/or actionsfor the service corresponding to service container 602. For example,service layers 608 may include an entry points layer that contains dataspecifying the entry points for the service. Service layers 608 may alsoinclude a matching layer that contains data related to a topology forCIs associated with the service. Further, service layers 608 may includean impact layer that stores data related to event management operations,such as impact rules that are assigned to CIs associated with theservice. Impact rules, which can be used for impact calculation,estimate the magnitude or severity of an outage based on one or moreaffected CIs. For example, an impact rule can define how impact appliesto parent or child entities that are part of a business service, or howcluster members affect an overall cluster status based on a percentageor number of cluster members.

In some embodiments, service layers 608 may be arranged hierarchicallyand have dependencies between one another. For instance, each individualservice layer may depend on the service layer(s) below the individualservice layer. As one example, service layer 1.3 may depend on servicelayer 1.2, which in turn may depend on service layer 1.1. CIs of anenvironment can be assigned to one of service layers 608.

The topology of a service model can include a graph or service map thatrepresents relationships between CIs associated with a service. Forinstance, the topology may be a visual representation that depictsparticular applications operating on particular computing devices in themanaged network as nodes in a graph. The edges of the graph mayrepresent physical and/or logical network connectivity between thesenodes. This visual representation allows users to rapidly determine theimpact of a problematic CI on the rest of the service. For instance,rather than viewing, in isolation, the properties of a databaseapplication, this application can be represented as having connectionsto other applications and the computing devices that rely upon orsupport the application. Thus, if the database is exhibiting a problem(e.g., running out of storage capacity), the impacted service(s) can beefficiently determined.

FIG. 7 provides an example service map including applications andcomputing devices that make up an email service that supports redundancyand high-availability. This service map may be generated for display onthe screen of a computing device. As noted above, the nodes in theservice map represent applications operating on computing devices. Thesenodes may take the form of icons related to the respective functions ofthe applications or computing devices.

The entry point to the email service, as designated by the largedownward-pointing arrow, may be load balancer 700. Load balancer 700 maybe represented with a gear icon, and may operate on a device with hostname maillb.example.com. This host name, as well as other host namesherein, may be a partially-qualified or fully-qualified domain name inaccordance with DNS domain syntax.

Load balancer 700 may distribute incoming requests across mailboxapplications 702, 704, 706, and 708 operating on mail server devicesmsrv1.example.com, msrv2.example.com, msrv3.example.com, andmsrv4.example.com, respectively. These mail server devices may berepresented by globe icons on the service map. Connectivity between loadbalancer 700 and each of mailbox applications 702, 704, 706, and 708 isrepresented by respective edges.

Mailbox applications 702, 704, 706, and 708 may, for instance, respondto incoming requests for the contents of a user's mail folder, for thecontent of an individual email message, to move an email message fromone folder to another, or to delete an email message. Mailboxapplications 702, 704, 706, and 708 may also receive and processincoming emails for storage by the email service. Other email operationsmay be supported by mailbox applications 702, 704, 706, and 708. Forsake of example, it may be assumed that mailbox applications 702, 704,706, and 708 perform essentially identical operations, and any one ofthese applications may be used to respond to any particular request.

The actual contents of users' email accounts, including email messages,folder arrangements, and other settings, may be stored in one or more ofmail database applications 710, 712, and 714. These applications mayoperate on database server devices db0.example.com, db1.example.com, andmdbx.example.com, which are represented by database icons on the networkmap. Connectivity between mailbox applications 702, 704, 706, and 708and each of mail database applications 710, 712, and 714 also isrepresented by respective edges.

Mailbox applications 702, 704, 706, and 708 may retrieve requested datafrom mail database applications 710, 712, and 714, and may also writedata to mail database applications 710, 712, and 714. The data stored bymail database applications 710, 712, and 714 may be replicated acrossall of the database server devices.

The arrangement of FIG. 7 may vary. For example, more or fewer loadbalancers, mailbox applications, mail database applications, as well astheir associated devices, may be present. Furthermore, additionaldevices may be included, such as storage devices, routers, switches, andso on. Additionally, while FIG. 7 is focused on an example emailservice, similar network maps may be generated and displayed for othertypes of services, such as web services, remote access services,automatic backup services, content delivery services, and so on.

Additionally, nodes representing devices of the same type or operatingthe same application or type of application may be placed at the samehorizontal level, as in FIG. 7. Nodes representing the entry point ofthe represented service may be placed at the top of the map, and thevertical arrangement of nodes may roughly correspond to the order inwhich the nodes become involved in carrying out operations of theservice. Nonetheless, as the number of nodes and connections grows, sucharrangements may vary for purposes of making presentation of the networkmap readable.

VII. Example Service Model Re-Computation

Synchronization between a CMDB, such as CMDB 500, and a service model,such as service model 600, can be maintained using a re-computationprocess. For instance, following a change in the CMDB, there-computation process can be used to recalculate the structure orproperties of the service model.

The change in the CMDB may include either a change to a CI attribute ora change to the topology of the service model (e.g., relations removed,relations, added, etc.). For a change affecting a given CI, there-computation process can involve updating the information for thegiven CI in the service model, and also re-building the topology of theservice model based on relations between the given CI and other CIs ofthe CMDB. Re-building the topology can involve identifying an entrypoint of a service to which the given CI relates, tracing the entrypoint to the given CI based on a set of relations between the given CIand the entry point, and resolving the set of relations into a graph.

Unfortunately, however, this re-computation process can be wasteful interms of consumption of memory and processing resources. For instance,for a CI change that does not affect a topology of the service model,recalculating the structure of the service model may be unnecessary. Toaddress this and potentially other issues, multiple re-computation modesare provided, from which an appropriate re-computation mode can beselected and carried out based on a type of change that is made to a CI.

By way of example, when a change is made to a CI record of a CMDB, aserver device can add a change record corresponding to the change to achange record table. The change record can specify a change type that isindicative of whether the change affects a topology of service model.The server device can use the change type specified in the change recordas a basis for selecting a service model re-computation mode from amonga plurality of service model re-computation modes, and re-compute aservice layer of the service model in accordance with the selectedservice model re-computation mode.

For instance, if a CI change does not affect a topology of the servicemodel, then, based on the CI change not affecting the topology, a fastre-computation mode can be selected rather than a full re-computationmode. In accordance with the fast re-computation mode, a CI record aschanged can be merged into the definition of the service model withouttraversing the database in search of changes to the topology of theservice model. On other hand, for a CI change that does affect atopology of the service model, the full re-computation mode can beselected.

In one example, when a full re-computation mode is selected,re-computing the service model can involve traversing the database basedon entry points of the service so as to re-map the topology of a servicelayer. For instance, the entry points of the service can be provided asinput to a topology builder. A CMDB walker of the topology builder canuse the entry points as a starting point, and then “walk” through CIrecords of the CMDB based on configuration data for the entry pointsthat specifies relations between the entry points and other CIs of theservice environment. As the CDMB walker traverses the CMDB, the topologybuilder can discover the CIs that the entry points are related to,discover other CIs in the environment that those CIs are related to, andso forth. After walking through CI records of the CMDB for CIs of theservice environment, the topology builder can then resolve the entrypoints, CIs, and relations into a graph of CIs, with the graphindicating relationships between the CIs. The resulting graph, and itsCIs and relations, can then be incorporated into the service model.

FIG. 8 depicts an example change record table 800. As noted above, aserver device can add change records to change record table 800 whenchanges are made to CI records of a CMDB. As shown in FIG. 8, eachchange record can specify a change type, service layer, serviceenvironment, CI identifier (ID), and status.

The change type can be indicative of whether the change affects atopology of the service model. In one example, the change type can beselected from one of four possible change types: topology change, CIchange, impact rule change, and special CI change. The change type oftopology change can be used for changes that affect the topology of theservice model. For instance, topology change can be used for changeswhere a relation between a first CI and a second CI is added, removed,or modified.

The change types of CI change, impact rule change, and special CI changecan be used for changes that do not affect a topology of the servicemodel. For changes that do not affect the topology but do modify animpact rule assigned to a CI, the change type of impact rule change canbe used. For changes that do not affect the topology but do modify oneor more particular fields of a CI record (e.g., a name field), thechange type of special CI change can be used. For changes that do notaffect the topology, do not modify impact rules, and do not modify oneor more of the particular fields, the change type of CI change can beused.

The service layer and service environment of a change record canreference a respective service layer and service environment that a CIis assigned to, while the CI ID can be an identifier of the CI.

Further, the status field of a change record can be used by a serverdevice to manage re-computation of the service model. For example, theserver device can re-compute service environments of the service modelone-by-one. When the server device determines that change record table800 includes at least one change record corresponding to a serviceenvironment, the server device can flag the service environment forre-computation. Further, the server device can then search throughchange record table for any service layers in that service environmenthaving a status of “WAITING” and change the status to “IN_PROCESS.”After a service layer is re-computed in accordance with the selectedservice model re-computation mode, the server device can change thestatus field for the service layer in change record table 800 to“PROCESSED”.

When the server device re-computes a service environment, the serverdevice can re-compute the service layers of the service environmentone-by-one based on the change types of the service layers. By way ofexample, for each service layer, a service model re-computation mode canbe selected based on the change type(s) for the change recordscorresponding to the service layer. For instance, for a service layerhaving a change record with change type of topology change, the serverdevice can select a full re-computation mode for the service layer. Whenmultiple change records having different change types correspond to asingle service layer, the re-computation mode for the service layer canbe determined based on the different change types.

FIG. 9 is a flow chart depicting example operations that can be carriedout to select a service model re-computation mode for a service layer.As shown in FIG. 9, at block 900, a server device can determine, withreference to a change record table, whether the service layer includesany change records having a type of CI change. Based on identifying atleast one change record for the service layer having a change type of CIchange, the server device can designate the service model re-computationmode as CI_CHANGES. This designation may be subsequently overridden,depending on the outcome of operations performed at blocks 902, 904, and906.

At block 902, the server device can then further determine whether theservice layer includes any change records having a change type of impactrule change. Based on identifying at least one change record for theservice layer having a change type of impact rule change, the serverdevice can designate the service model re-computation mode asIMPACT_RULE_CHANGES. This designation may be subsequently overridden,depending on the outcome of operations performed at blocks 904 and 906.

At block 904, the server device can then further determine whether theservice layer includes any change records having a change type ofspecial CI change. Based on identifying at least one change record forthe service layer having a change type of special CI changes, the serverdevice can designate the service model re-computation mode asSPECIAL_CI_CHANGES. This designation may also be subsequentlyoverridden, depending on the outcome of the operation performed at block906.

At block 906, the server device can then determine whether the servicelayer includes any change records having a change type of topologychange. Based on identifying at least one change record for the servicelayer having a change type of topology change, the server device candesignate the service model re-computation mode as MIXED. Therefore, theservice model re-computation mode that is selected for the service layeris the mode designated after the operations at blocks 900, 902, 904, and906 have been carried out.

The CI_CHANGES mode, the IMPACT_RULE_CHANGES mode, and theSPECIAL_CI_CHANGES mode can be fast re-computation modes. As notedabove, as part of a fast-recomputation mode, a CI record as changed canbe merged into the definition of the service model without traversing aCMDB in search of changes to the topology of the service model. Theoperations carried out in accordance with these three fastre-computation modes may, however, vary based on whether the mode isCI_CHANGES, IMPACT_RULE_CHANGES, or SPECIAL_CI_CHANGES. For instance,re-computing the service layer in accordance with theIMPACT_RULE_CHANGES mode can include providing an impact-rule-changenotification to an event management service. As another example,re-computing the service layer in accordance with the SPECIAL_CI_CHANGESmode can include providing a name-change notification to the eventmanagement service.

The MIXED mode can be a full re-computation mode. Hence, re-computingthe service layer in accordance with the MIXED mode can includetraversing a CMDB based on entry points of a service so as to re-map thetopology of the service layer.

In some examples, the server device can select a service modelre-computation mode for a service layer of a service environment basedon the service model re-computation mode that is selected for a previouslayer of the service environment. For instance, with reference toservice environment 604 of FIG. 6, the server device can select aservice model re-computation layer for service layer 1.2 based on theservice model re-computation mode that is selected for service layer1.1. Similarly, the server device can select a service modelre-computation layer for service layer 1.3 based on the service modelre-computation mode that is selected for service layer 1.2.

In some cases, it may be desirable to select the service modelre-computation mode for a service layer based on the service modelre-computation mode of a previous layer. For instance, a fullre-computation mode may have been selected for a previous service layerdue to the presence of a topology change for a CI of the previousservice layer. Since the topology change could affect other servicelayers, selecting the full re-computation mode for other service layersof the service environment can help to make sure the service model isupdated to account for any topology changes within the serviceenvironment.

FIG. 10 is a flow chart depicting example operations that can be carriedout to select a service model re-computation mode for a service layerbased on the service model re-computation mode selected for a previousservice layer. Within FIG. 10, current mode refers to the currentservice model re-computation mode that is selected for a service layerbased on change types of change records for the service layer. Further,previous mode refers to the service model re-computation mode that isselected for the previous service layer (e.g., a service layer that isimmediately below the service layer hierarchically). The operations ofFIG. 10 could be carried out as part of a process that receives as inputa current mode for a service layer and a previous mode for the previousservice layer and outputs (i.e., returns) either the current mode or theprevious mode as a service model re-computation mode for the servicelayer.

As shown in FIG. 10, at block 1000, the server device determines whetherthe current mode is UNKNOWN. The current mode could, for instance, beunknown if there are not any change records corresponding to the servicelayer in the change record table. In some instances, when the serverdevice re-computes a service environment, the server device mayre-compute all service layers of that service environment. Hence, it ispossible that the change record table might not include any changerecords corresponding to the service layer in which case the currentmode would be UNKNOWN. Based on determining that the current mode isUKNOWN, the server device can then, at block 1002, determine whether theprevious mode exists. If the previous mode exists, the previous mode isreturned. Whereas, if the previous mode does not exist, the current mode(i.e., UNKNOWN) is returned. The UKNOWN mode is a full re-computationmode.

Based on determining that the current mode is not UNKNOWN, at block1004, the server device determines whether the current mode isCI_CHANGES. Based on determining that the current mode is CI_CHANGES,the server device can then, at block 1006, determine whether theprevious mode exists. If the previous mode exists, the previous mode isreturned. Whereas, if the previous mode does not exist, the current mode(i.e., CI_CHANGES) is returned.

Based on determining that the current mode is not CI_CHANGES, at block1008, the server device determines whether the current mode isIMPACT_RULE_CHANGES. Based on determining that the current mode isIMPACT_RULE_CHANGES, the server device can then, at block 1010,determine whether the previous mode exists and is not equal toCI_CHANGES. If the previous mode exists and is not equal to CI_CHANGES,the previous mode is returned. Whereas, if the previous mode does notexist or is equal to CI_CHANGES, the current mode (i.e.,IMPACT_RULE_CHANGES) is returned. In other words, based on thedetermination at block 1010, the returned mode is eitherIMPACT_RULE_CHANGES, SPECIAL_CI_CHANGES, or MIXED. This can ensure that,if the previous service layer or the current service layer includes aspecial CI change or a topology change, the re-computation mode for theservice layer will be determined based on the previous mode, so that theservice layer can be re-computed as appropriate to account for thespecial CI change or the topology change.

Based on determining that the current mode is not IMPACT_RULES_CHANGES,at block 1012, the server device determines whether the current mode isSPECIAL_CI_CHANGES. Based on determining that the current mode isSPECIAL_CI_CHANGES, the server device can then, at block 1014, determinewhether the previous mode exists and is not equal to CI_CHANGES and isalso not equal to IMPACT_RULE_CHANGES. If the previous mode exists andis not equal to CI_ CHANGES and is also not equal toIMPACT_RULE_CHANGES, the previous mode is returned. Whereas, if theprevious mode does not exist or is equal to CI_CHANGES or is equal toIMPACT_RULE_CHANGES, the current mode (i.e., SPECIAL_CI_CHANGES) isreturned.

Based on determining that the current mode is not SPECIAL_CI_CHANGES, atblock 1016, the server device determines whether the current mode isMIXED. Based on determining that the current mode is MIXED, the currentmode is returned. As noted above, the MIXED mode is a fullre-computation mode.

VIII. Example Operations

FIG. 11 is a flow chart illustrating an example embodiment. The processillustrated by FIG. 11 may be carried out by a computing device, such ascomputing device 100, and/or a cluster of computing devices, such asserver cluster 200. However, the process can be carried out by othertypes of devices or device subsystems. For example, the process could becarried out by a portable computer, such as a laptop or a tablet device.

The embodiments of FIG. 11 may be simplified by the removal of any oneor more of the features shown therein. Further, these embodiments may becombined with features, aspects, and/or implementations of any of theprevious figures or otherwise described herein.

Block 1100 of FIG. 11 may involve maintaining, by one or more computingdevices of a computational instance, a database that contains aplurality of CI records corresponding to a set of computing deviceswithin a managed network, a set of software applications configured toexecute on the set of computing devices, and a network-based servicethat is provided by execution of the set of software applications. Themanaged network may be associated with the computational instance. Inaddition, the database may contains a definition of a service model thatrepresents the set of computing devices, the set of softwareapplications, and relationships therebetween that facilitate providingthe network-based service. Further, the service model may include aservice environment having multiple service layers that arehierarchically-arranged.

Block 1102 of FIG. 11 may involve receiving, by the one or morecomputing devices from the managed network, an indication of a change toa CI record of the plurality of CI records.

Block 1104 of FIG. 11 may involve storing, in the database, the CIrecord as changed.

Block 1106 of FIG. 11 may involve adding, by the one or more computingdevices to a change record table stored within the database, a changerecord corresponding to the change to the CI record. The change recordmay (i) reference the CI record and a service layer of the multipleservice layers, and (ii) specify a change type that is indicative ofwhether the change affects a topology of the service model.

Block 1108 of FIG. 11 may involve selecting, by the one or morecomputing devices based on the change type, for the service layer aservice model re-computation mode from among a plurality of servicemodel re-computation modes.

Block 1110 of FIG. 11 may involve re-computing, by the one or morecomputing devices, the service layer of the service environment inaccordance with the service model re-computation mode.

In some cases, the change type indicates that the change does not affectthe topology, and selecting the service model re-computation model mayinvolve selecting a fast re-computation mode rather than a fullre-computation mode that consumes more memory when carried out than thefast re-computation mode. In these embodiments, re-computing the servicelayer of the service environment in accordance with the fastre-computation mode may involve merging the CI record as changed intothe service model without traversing the database in search of changesto the topology of the service model.

Additionally, the change type may further indicate that the change is animpact rule change, in which case re-computing the service layer of theservice environment in accordance with the fast re-computation mode mayfurther involve providing an impact-rule-change notification to an eventmanagement service disposed within the remote network managementplatform. Alternatively, the change type may further indicate that thechange is a change to a name field of the CI record, in whichre-computing the service layer of the service environment in accordancewith the fast re-computation mode may further involve providing aname-change notification to an event management service disposed withinthe remote network management platform.

In some cases, the change type indicates that the change affects thetopology, and selecting the service model re-computation mode involvesselecting a full re-computation mode rather than a fast re-computationmode that consumes less memory when carried out than the fullre-computation mode. In these embodiments, re-computing the servicelayer of the service environment in accordance with the fullre-computation mode may involve traversing the database based on entrypoints of the network-based service so as to re-map the topology of theservice layer. These embodiments of FIG. 11 may further involve (i)receiving, from the managed network, an indication of a second change toa second CI record of the plurality of CI records; (ii) adding, to thechange record table, a second change record corresponding to the secondchange to the second CI record, wherein the second change recordreferences the second CI record and a second service layer within theservice environment and specifies a second change type that isindicative of whether the second change affects the topology; (iii)selecting for the second service layer, based on the change type and thesecond change type, a second service model re-computation mode fromamong the plurality of service model re-computation modes; and (iv)re-computing the second service layer of the service environment inaccordance with the second service model re-computation mode. In theseembodiments, the second change type may indicate that the second changedoes not affect the topology, but selecting the second service modelre-computation mode may involve selecting the full re-computation modebased on the service model re-computation mode for the service layerbeing the full re-computation mode even though the second change doesnot affect the topology.

Some of the embodiments of FIG. 11 may further involve flagging theservice environment for re-computation based on a reference to theservice layer within the service environment. Additionally oralternatively, in some of the embodiments of FIG. 11, re-computing theservice layer of the service environment in accordance with the servicemodel re-computation mode may involve creating a snapshot of thenetwork-based service. The snapshot may specify a time indicative ofwhen the re-computing is completed.

IX. Conclusion

The present disclosure is not to be limited in terms of the particularembodiments described in this application, which are intended asillustrations of various aspects. Many modifications and variations canbe made without departing from its scope, as will be apparent to thoseskilled in the art. Functionally equivalent methods and apparatuseswithin the scope of the disclosure, in addition to those describedherein, will be apparent to those skilled in the art from the foregoingdescriptions. Such modifications and variations are intended to fallwithin the scope of the appended claims.

The above detailed description describes various features and operationsof the disclosed systems, devices, and methods with reference to theaccompanying figures. The example embodiments described herein and inthe figures are not meant to be limiting. Other embodiments can beutilized, and other changes can be made, without departing from thescope of the subject matter presented herein. It will be readilyunderstood that the aspects of the present disclosure, as generallydescribed herein, and illustrated in the figures, can be arranged,substituted, combined, separated, and designed in a wide variety ofdifferent configurations.

With respect to any or all of the message flow diagrams, scenarios, andflow charts in the figures and as discussed herein, each step, block,and/or communication can represent a processing of information and/or atransmission of information in accordance with example embodiments.Alternative embodiments are included within the scope of these exampleembodiments. In these alternative embodiments, for example, operationsdescribed as steps, blocks, transmissions, communications, requests,responses, and/or messages can be executed out of order from that shownor discussed, including substantially concurrently or in reverse order,depending on the functionality involved. Further, more or fewer blocksand/or operations can be used with any of the message flow diagrams,scenarios, and flow charts discussed herein, and these message flowdiagrams, scenarios, and flow charts can be combined with one another,in part or in whole.

A step or block that represents a processing of information cancorrespond to circuitry that can be configured to perform the specificlogical functions of a herein-described method or technique.Alternatively or additionally, a step or block that represents aprocessing of information can correspond to a module, a segment, or aportion of program code (including related data). The program code caninclude one or more instructions executable by a processor forimplementing specific logical operations or actions in the method ortechnique. The program code and/or related data can be stored on anytype of computer readable medium such as a storage device including RAM,a disk drive, a solid state drive, or another storage medium.

The computer readable medium can also include non-transitory computerreadable media such as computer readable media that store data for shortperiods of time like register memory and processor cache. The computerreadable media can further include non-transitory computer readablemedia that store program code and/or data for longer periods of time.Thus, the computer readable media may include secondary or persistentlong term storage, like ROM, optical or magnetic disks, solid statedrives, compact-disc read only memory (CD-ROM), for example. Thecomputer readable media can also be any other volatile or non-volatilestorage systems. A computer readable medium can be considered a computerreadable storage medium, for example, or a tangible storage device.

Moreover, a step or block that represents one or more informationtransmissions can correspond to information transmissions betweensoftware and/or hardware modules in the same physical device. However,other information transmissions can be between software modules and/orhardware modules in different physical devices.

The particular arrangements shown in the figures should not be viewed aslimiting. It should be understood that other embodiments can includemore or less of each element shown in a given figure. Further, some ofthe illustrated elements can be combined or omitted. Yet further, anexample embodiment can include elements that are not illustrated in thefigures.

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments will be apparent to those skilled in the art.The various aspects and embodiments disclosed herein are for purpose ofillustration and are not intended to be limiting, with the true scopebeing indicated by the following claims.

What is claimed is:
 1. A computational instance of a remote networkmanagement platform comprising: a database that contains a plurality ofconfiguration item (CI) records corresponding to a set of computingdevices disposed within a managed network, a set of softwareapplications configured to execute on the set of computing devices, anda network-based service that is provided by execution of the set ofsoftware applications, wherein the managed network is associated withthe computational instance, wherein the database contains a definitionof a service model that represents the set of computing devices, the setof software applications, and relationships therebetween that facilitateproviding the network-based service, and wherein the service modelincludes a service environment having multiple service layers that arehierarchically-arranged within the service environment; and one or moreserver devices configured to: receive, from the managed network, anindication of a change to a CI record of the plurality of CI records;store, in the database, the CI record as changed; add, to a changerecord table stored within the database, a change record correspondingto the change to the CI record, wherein the change record: (i)references the CI record and a service layer of the multiple servicelayers, and (ii) specifies a change type that is indicative of whetherthe change affects a topology of the service model; based on the changetype, select for the service layer a service model re-computation modefrom among a plurality of service model re-computation modes; andre-compute the service layer of the service environment in accordancewith the service model re-computation mode.
 2. The computationalinstance of claim 1, wherein the change type indicates that the changedoes not affect the topology, and wherein selecting the service modelre-computation mode comprises selecting a fast re-computation moderather than a full re-computation mode that consumes more memory whencarried out than the fast re-computation mode.
 3. The computationalinstance of claim 2, wherein re-computing the service layer of theservice environment in accordance with the fast re-computation modecomprises merging the CI record as changed into the service modelwithout traversing the database in search of changes to the topology ofthe service model.
 4. The computational instance of claim 3, wherein thechange type further indicates that the change is an impact rule change,and wherein re-computing the service layer of the service environment inaccordance with the fast re-computation mode further comprises providingan impact-rule-change notification to an event management servicedisposed within the remote network management platform.
 5. Thecomputational instance of claim 3, wherein the change type furtherindicates that the change is a change to a name field of the CI record,and wherein re-computing the service layer of the service environment inaccordance with the fast re-computation mode further comprises providinga name-change notification to an event management service disposedwithin the remote network management platform.
 6. The computationalinstance of claim 1, wherein the change type indicates that the changeaffects the topology, wherein selecting the service model re-computationmode comprises selecting a full re-computation mode rather than a fastre-computation mode that consumes less memory when carried out than thefull re-computation mode.
 7. The computational instance of claim 6,wherein re-computing the service layer of the service environment inaccordance with the full re-computation mode comprises traversing thedatabase based on entry points of the network-based service so as tore-map the topology of the service layer.
 8. The computational instanceof claim 6, wherein the one or more server devices are furtherconfigured to: receive, from the managed network, an indication of asecond change to a second CI record of the plurality of CI records; add,to the change record table, a second change record corresponding to thesecond change to the second CI record, wherein the second change record:references the second CI record and a second service layer of within theservice environment, and specifies a second change type that isindicative of whether the second change affects the topology; selectingfor the second service layer, based on the change type and the secondchange type, a second service model re-computation mode from among theplurality of service model re-computation modes; and re-computing thesecond service layer of the service environment in accordance with thesecond service model re-computation mode.
 9. The computational instanceof claim 8, wherein the second change type indicates that the secondchange does not affect the topology, and wherein selecting the secondservice model re-computation mode comprises selecting the fullre-computation mode based on the service model re-computation mode forthe service layer being the full re-computation mode even though thesecond change does not affect the topology.
 10. The computationalinstance of claim 1, wherein the one or more server devices are furtherconfigured to flag the service environment for re-computation based on areference to the service layer within the service environment.
 11. Thecomputational instance of claim 1, wherein re-computing the servicelayer of the service environment in accordance with the service modelre-computation mode comprises creating a snapshot of the network-basedservice, wherein the snapshot specifies a time indicative of when there-computing is completed.
 12. A method comprising: maintaining, by oneor more server devices of a computational instance, a database thatcontains a plurality of configuration item (CI) records corresponding toa set of computing devices within a managed network, a set of softwareapplications configured to execute on the set of computing devices, anda network-based service that is provided by execution of the set ofsoftware applications, wherein the managed network is associated withthe computational instance, wherein the database contains a definitionof a service model that represents the set of computing devices, the setof software applications, and relationships therebetween that facilitateproviding the network-based service, and wherein the service modelincludes a service environment having multiple service layers that arehierarchically-arranged; receiving, by the one or more server devices,from the managed network, an indication of a change to a CI record ofthe plurality of CI records; storing, in the database, the CI record aschanged; adding, by the one or more server devices, to a change recordtable stored within the database, a change record corresponding to thechange to the CI record, wherein the change record: (i) references theCI record and a service layer of the multiple service layers, and (ii)specifies a change type that is indicative of whether the change affectsa topology of the service model; based on the change type, selecting, bythe one or more server devices, for the service layer a service modelre-computation mode from among a plurality of service modelre-computation modes; and re-computing, by the one or more serverdevices, the service layer of the service environment in accordance withthe service model re-computation mode.
 13. The method of claim 12,wherein the change type indicates that the change does not affect thetopology, and wherein selecting the service model re-computation modecomprises selecting a fast re-computation mode rather than a fullre-computation mode that consumes more memory when carried out than thefast re-computation mode.
 14. The method of claim 13, whereinre-computing the service layer of the service environment in accordancewith the fast re-computation mode comprises merging the CI record aschanged into the service model without traversing the database in searchof changes to the topology of the service model.
 15. The method of claim14, wherein the change type further indicates that the change is animpact rule change, and wherein re-computing the service layer of theservice environment in accordance with the fast re-computation modefurther comprises providing an impact-rule-change notification to anevent management service.
 16. The method of claim 14, wherein the changetype further indicates that the change is a change to a name field ofthe CI record, and wherein re-computing the service layer of the serviceenvironment in accordance with the fast re-computation mode furthercomprises providing a name-change notification to an event managementservice.
 17. The method of claim 12, wherein the change type indicatesthat the change affects the topology, wherein selecting the servicemodel re-computation mode comprises selecting a full re-computation moderather than a fast re-computation mode that consumes less memory whencarried out than the full re-computation mode.
 18. The method of claim17, wherein re-computing the service layer of the service environment inaccordance with the full re-computation mode comprises traversing thedatabase based on entry points of the network-based service so as tore-map the topology of the service layer.
 19. The method of claim 12,wherein re-computing the service layer of the service environment inaccordance with the service model re-computation mode comprises creatinga snapshot of the network-based service, wherein the snapshot specifiesa time indicative of when the re-computing is completed.
 20. An articleof manufacture including a non-transitory computer-readable medium,having stored thereon program instructions that, upon execution by oneor more server devices of a computational instance of a remote networkmanagement platform, cause the one or more server devices to performoperations comprising: maintaining a database that contains a pluralityof configuration item (CI) records corresponding to a set of computingdevices within a managed network, a set of software applicationsconfigured to execute on the set of computing devices, and anetwork-based service that is provided by execution of the set ofsoftware applications, wherein the managed network is associated withthe computational instance, wherein the database contains a definitionof a service model that represents the set of computing devices, the setof software applications, and relationships therebetween that facilitateproviding the network-based service, and wherein the service modelincludes a service environment having multiple service layers that arehierarchically-arranged; receiving, from the managed network, anindication of a change to a CI record of the plurality of CI records;storing, in the database, the CI record as changed; adding, to a changerecord table stored within the database, a change record correspondingto the change to the CI record, wherein the change record: (i)references the CI record and a service layer of the multiple servicelayers, and (ii) specifies a change type that is indicative of whetherthe change affects a topology of the service model; based on the changetype, selecting for the service layer a service model re-computationmode from among a plurality of service model re-computation modes; andre-computing the service layer of the service environment in accordancewith the service model re-computation mode.